I came across this yesterday and tried to wrap my head around the problem. I thought our KOP was missing something, but after going through the checklist again, it wasn't. Someone wasn't thinking when they decided to switch to the AndyMark wheels with 1/2" bearings while keeping the 3/8" kit chassis.
I just made a quick trip to Home Depot and picked up some 3/8" ID x 1/2" OD aluminum tube (and bolts, wires, and the sort). It slips over the 3/8" bolts and works well with the bearings.